The Heart

Question 1

Structure

Answer 1

-right = deox blood to lungs

=left ox blood to lungs

Question 2

left ventricle

Answer 2

• thicker more muscular walls than right ventrile
• allows to contract more powerfully and pump blood all way around the body
• right side less muscular so contraction are only powerful enough to pump blood to the nearby lungs

Question 3

-ventricles

Answer 3

• thicker walls than the atria therefore they can push blood out of the heart
• whereas atria just need to push blood a short distance into the ventricles

Question 4

AV valves

Answer 4

-link atria to ventricles and stop blood flowing back into atria when the ventricles contract

Question 5

Semi-Lunar valves

Answer 5

-link ventricles to pulmonary artery to aorta and stop blood flowing back into the heart after the ventricles contract

Question 6

cords

Answer 6

-attach the av valves to ventricles to stop them being forced up into atria when the ventricles contract

Question 7

-heart valves

Answer 7

• only open one way whether they’re opened or closed depends on relative pressure of the heart chambers
• high pressure behind a valve its forced open so pressure higher in front so its forced shut
• flow of blood is unidirectional so it flows in one direction

Question 8

Cardiac Cycle

Answer 8

-ongoing sequence of contractions and relaxation of the atria and ventricles that keeps blood continuously circulating round the body

Question 9

ventricles relax and atria contract

Answer 9

• ventricles relaxed
• atria contract decreasing volume pressure of chambers and increasing the pressure inside the chambers so pushes blood into ventricle
• slight increase in ventricular pressure and chamber volume as ventricles receive the ejected blood from contracting atria

Question 10

ventricles contract atria relax

Answer 10

• the atria relax
• ventricles contract increasing their pressure so it becomes higher in ventricles than atria forcing av valves to shut to prevent back-flow
• pressure in ventricles higher than aorta and pulmonary artery which forces open semilunar valves and blood forced out into these arteries

Question 11

ventricles relax and atria relax

Answer 11

• both relax
• higher pressure in pulmonary artery and aorta closes the semilunar valves to prevent backflow into ventricles
• blood returns to heart and atria fill again due to higher pressure in vena cava and pulmonary vein
• in turns starts to increase pressure of the atria-as ventricles continue to relax their pressure falls below the pressure of atria so av valves open
• allows blood to flow passively without being pushed by atrial contraction into ventricles from atria
• atria contract and whole process begins again

Question 12

cardiac output

Answer 12

-stroke volume x heart rate

Question 13

stroke volume

Answer 13

-volume of blood pumped during each heartbeat